Which of the following is a negative ligand?

$A$ coordination complex compound of cobalt has a molecular formula containing five ammonia molecules,one nitro group,and two chlorine atoms for one cobalt atom. One mole of this compound produces three moles of ions in an aqueous solution,and upon reacting with an excess of $AgNO_3$,it forms $AgCl$ precipitate. The ionic formula for this complex would be:

The total number of ions present in $K_4[Fe(CN)_6]$ is .....

Which of the following is the formula of tartar emetic?

Coordination number of $Fe$ in the complexes $[Fe(CN)_6]^{4-}$,$[Fe(CN)_6]^{3-}$ and $[FeCl_4]^{-}$ would be respectively

The denticity of the ligand present in the Fehling's reagent is $..........$.